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Contents lists available at ScienceDirect

Veterinary Parasitology

jou rnal homepage: www.elsevier.com/locate/vetpar

Taxonomy and molecular epidemiology of granulosus

sensu lato

∗

T. Romig , D. Ebi, M. Wassermann

Universität Hohenheim, FG Parasitologie 220 B, 70599 Stuttgart, Germany

a r t i c l e i n f o a b s t r a c t

Keywords: Echinococcus granulosus, formerly regarded as a single species with a high genotypic and phenotypic

Echinococcus granulosus

diversity, is now recognised as an assemblage of cryptic species, which differ considerably in morphol-

Taxonomy

ogy, development, host specificity (including infectivity/pathogenicity for humans) and other aspects.

Nomenclature

This diversity is reflected in the mitochondrial and nuclear genomes and has led to the construction of

Molecular epidemiology

phylogenetic trees and hypotheses on the origin and geographic dispersal of various taxa. Based on phe-

notypic characters and gene sequences, E. granulosus (sensu lato) has by now been subdivided into E.

granulosus sensu stricto (including the formerly identified genotypic variants G1-3), Echinococcus felidis

(the former ‘lion strain’), Echinococcus equinus (the ‘horse strain’, genotype G4), Echinococcus ortleppi (the

‘cattle strain’, genotype G5) and Echinococcus canadensis. The latter species, as recognised here, shows

the highest diversity and is composed of the ‘camel strain’, genotype G6, the ‘pig strain’, genotype G7,

and two ‘cervid strains’, genotypes G8 and G10. There is debate whether the closely related G6 and

G7 should be placed in a separate species, but more morphological and biological data are needed to

support or reject this view. In this classification, the application of rules for zoological nomenclature

led to the resurrection of old species names, which had before been synonymised with E. granulosus.

This nomenclatural subdivision of the agents of cystic echinococcosis (CE) may appear inconvenient for

practical applications, especially because molecular tools are needed for identification of the cyst stage,

and because retrospective data on ‘E. granulosus’ are now difficult to interpret without examination of

voucher specimens. However, the increased awareness for the diversity of CE agents – now emphasised

by species names rather than genotype numbers – has led to a large number of recent studies on this issue

and a rapid increase of knowledge on geographical spread, host range and impact on human health of the

various species. E. granulosus s.s., often transmitted by sheep, is now clearly identified as the principal

CE agent affecting humans. Contrary to previous assumptions, genotypes G6/7 of E. canadensis readily

infect humans, although CE incidences are rather low where E. canadensis predominates. Sub-Saharan

Africa seems to be the region with the highest diversity of Echinococcus, and wild carnivores may play

a more important role in the lifecycles of various species than previously assumed. Still, a number of

issues remain unclear, e.g. possibly diverging parameters of diagnostic tests among the species, different

responses to vaccines and, importantly, possibly required modifications of clinical management due to

differences in pathogenicity.

© 2015 Elsevier B.V. All rights reserved.

1. A summarised history of Echinococcus nomenclature and

taxonomy

1.1. Early period

Echinococcosis of humans and livestock has been known – and

named in various languages – since antiquity. After the introduc-

∗

Corresponding author at: Universität Hohenheim, FG Parasitologie 220 B, Emil-

tion of modern zoological nomenclature in 1758, intended to bring

Wolff-Str. 34, 70599 Stuttgart, Germany. Fax: +49 711 459 22276.

order into the infinite number of poorly defined local names for

E-mail addresses: [email protected] (T. Romig),

, naming of what we define today as Echinococcus spp.

[email protected] (D. Ebi), [email protected]

(M. Wassermann). became rather chaotic initially. No less than 85 bi- or trinomial

http://dx.doi.org/10.1016/j.vetpar.2015.07.035

0304-4017/© 2015 Elsevier B.V. All rights reserved.

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

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Table 1

Synopsis of relevant descriptions of species and subspecies. Agents of cystic echinococcosis (E. granulosus sensu lato) in bold print.

Original name (description) Original description from (stage, host, country) Current name

Hydatigena granulosa Batsch (1796) Metacestode, sheep, Germany Echinococcus granulosus

Taenia multilocularis Leuckart (1863) Metacestode, human, Germany E. multilocularis

T. oligarthra Diesing (1863) Adult, puma, Brazil E. oligarthra

Echinococcus cruzi Brumpt and Joyeux (1924) Metacestode, agouti, Brazil E. oligarthra

E. minimus Cameron (1926) Adult, wolf, Europe E. granulosus

E. longimanubrius Cameron (1926) Adult, African wild dog, South Africa E. granulosus

E. cameroniOrtlepp (1934) Adult, red fox, Britain E. granulosus

a

E. lycaontis Ortlepp (1934) Adult, African wild dog , South Africa E. granulosus

E. felidis Ortlepp (1937) Adult, lion, South Africa E. felidis

b

E. intermediusLopez-Neyra and Soler Planas (1943) Adult, dog, Spain E. granulosus

E. ortleppi Lopez-Neyra and Soler Planas (1943) Adult, dog, South Africa E. ortleppi

E. sibiricensis Rausch and Schiller (1954) Adult, arctic fox, St. Lawrence Isl. E. multilocularis

E. patagonicus Szidat (1960) Adult, Lycalopex, Argentina E. granulosus

c b

E. granulosus canadensisWebster and Cameron (1961) Metacestode , reindeer, Canada E. canadensis

c b

E. granulosus borealis Sweatman and Williams (1963) Metacestode , moose, Canada E. canadensis

d

E. granulosus equinusWilliams and Sweatman (1963) Adult, dog , Britain E. equinus

e

E. granulosus africanus Verster (1965) Adult , div. Canidae, South Africa E. granulosus

E. pampeanus Szidat (1967) Adult, Leopardus colocolo, Argentina E. oligarthra

E. granulosus dusicyontis Blood and Lelijveld (1969) Adult, Lycalopex, Argentina E. granulosus

E. cepanzoiSzidat (1971) Adult, Lycalopex, Argentina E. granulosus

E. vogeli Rausch and Bernstein (1972) Adult, bush dog, Ecuador E. vogeli

E. shiquicus Xiao et al. (2005) Adult, , China E. shiquicus

E. russicensis Tang et al. (2007) Adult, corsac fox, China E. multilocularis

a

From cyst of sheep origin.

b

Species status under evaluation.

c

Supplemented by adult worms from experimental infections.

d

From cyst of horse origin.

e

From cyst of cattle origin.

Latinised names were published until the end of the 19th century, morphology, e.g. differences in the number of proglottids, rostellar

almost all of them based on metacestodes of various morpholog- hook morphology, number and distribution of testes and position

ical appearance and host origin (Abuladze, 1964). The first valid of the genital pore. In addition to E. granulosus (Batsch, 1786) and E.

name of these was Hydatigena granulosa, given by Batsch in 1786 multilocularis Leuckart, 1863 – whose descriptions were based on

1

and recognisably based on a fertile Echinococcus cyst of sheep ori- metacestodes – Echinococcus oligarthra was described by Diesing

gin from Germany. Shortly after, Rudolphi established the genus (as Taenia) as early as 1863 (later, the metacestode was sepa-

Echinococcus in 1801, the name referring to the small, round, ‘spiny’ rately described under the synonym E. cruzi Brumpt and Joyeux,

protoscolices found in the cysts, and thus created the combina- 1924). Echinococcus minimus and Echinococcus longimanubrius were

tion E. granulosus, which is still in use today. Not recognising the described by Cameron (1926) from a European (Macedonian)

link between metacestodes and adult worms, Rudolphi described wolf and an African wild dog, respectively (Brumpt and Joyeux,

adult Echinococcus from a dog as Taenia cateniformis in 1808. An 1924; Cameron, 1926; Diesing, 1863). Ortlepp added Echinococcus

additional description of adult worms was provided by Beneden in cameroni (for worms from a British fox that Cameron had iden-

1856, as Taenia nana, in ignorance of the fact that three years ear- tified earlier as E. granulosus) and Echinococcus lycaontis (from an

lier the relationship between cysts and adult worms in dogs had African wild dog), followed by Echinococcus felidis from an African

already been proven after independent feeding experiments by von lion (Ortlepp, 1934; Ortlepp, 1937). Echinococcus sibiricensis Rausch

Siebold and Küchenmeister. Eventually, at the end of the 19th cen- and Schiller, 1954 was shortly after description synomymised E.

tury, the common name E. granulosus referred to all stages of the multilocularis (Vogel, 1955; Vogel, 1957). This was followed by

lifecycle, although synonyms like Taenia echinococcus remained in the descriptions of E. intermedius and E. ortleppi (Lopez-Neyra and

use for a long time after. Despite the large number of names that Soler Planas, 1943) from domestic dogs in Spain and South Africa,

had been given to cysts due to their morphological appearances, respectively, and Echinococcus patagonicus (Szidat, 1960), from a

echinococcosis eventually was commonly assumed to be caused wild South American canid (Lycalopex culpaeus) (Lopez-Neyra and

by a single species. Even the metacestode of alveolar echinococco- Soler Planas, 1943; Szidat, 1960). However, in a concise evaluation

sis (described as Echinococcus multilocularis Leuckart, 1863) with of published morphological data, Rausch and Nelson sank most of

its extremely divergent morphology and pathology in humans, and these names as synonyms under E. granulosus, mainly on grounds of

its peculiar geographical restriction, was viewed by the majority of uncertainty about the extent of variability of the diagnostic charac-

authors (the ‘unicists’) as a modification of E. granulosus. The ‘dual- ters used (Rausch and Nelson, 1963). Only two additional species,

ists’ – postulating a different species causing this disease – were in E. multilocularis and E. oligarthra, were considered valid by these

defensive position until the 1950s, when the lifecycle of E. multiloc- authors, while E. felidis and E. patagonicus were given uncertain sta-

ularis was discovered almost simultaneously on St. Lawrence Island tus awaiting further data. A further five species were described later

off Alaska and in central Europe (lit. in Abuladze, 1964; Tappe et al., on, of which E. pampeanus Szidat, 1967 and E. cepanzoi Szidat, 1971

2010). were synonymised with E. oligarthra and E. granulosus, respectively

(Schantz et al., 1976), and E. russicensis Tang et al., 2007 is now

thought to be a variant of E. multilocularis (Nakao et al., 2013a).

1.2. Species

Despite the debate whether echinococcosis might be caused by

one or by two species, a substantial number of additional Echinococ- 1

For the spelling of Echinococcus oligarthra (vs. E. oligarthrus) see Hüttner and

cus species had meanwhile been described based on adult worm Romig, 2009 and Nakaoet al.

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

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Table 2

were subsequently synonymised with E. oligarthra and E. granulo-

Current concept of Echinococcus taxonomy (agents of cystic echinococcosis in bold).

sus, respectively (Schantz et al., 1976).

Species Genotypes and strains

1.4. Strains and genotypes

Echinococcus granulosus Batsch (1796) G1-3, sheep / buffalo

strains

E. equinus Williams and Sweatman (1963) G4, horse strain At the beginning of the 1980s, there were finally four undis-

E. ortleppi Lopez-Neyra and Soler Planas (1943) G5, cattle strain

puted species (E. granulosus, E. multilocularis, E. oligarthra and E.

E. canadensis Webster and Cameron (1961) G6-7, camel-pig strain G8,

vogeli) (Kumaratilake and Thompson, 1982). It was clear, however,

American‘ cervid strain

that E. granulosus contained a substantial number of variants with

G10, Fennoscandian‘ cervid

strain differences concerning morphology, host specificity, biochemical

E. felidis Ortlepp (1937) lion strain

parameters, developmental biology and geographical distribution.

E. multilocularis Leuckart (1863)

Although the application of the biological species concept by

E. shiquicus Xiao et al. (2005)

Rausch (1967), which had led to the abolishment of all sym-

E. oligarthra Diesing (1863)

E. vogeli Rausch and Bernstein (1972) patric subspecies, had received criticism (Beveridge, 1974), no

attempt was made to resurrect subspecies names for these vari-

ants. Instead, an informal system of intraspecific ‘strains’ was

gradually established. This term was used to describe variants

Only E. vogeli Rausch and Bernstein, 1972 and E. shiquicus Xiao

that differed from each other in characters of epidemiological sig-

et al., 2005 are now considered to be valid species (Nakao et al.,

nificance (Thompson and McManus, 2001). Fully developed, the

2013a) (Table 1) ). Their phylogenetic relationships, based on four

system comprised eleven strains, namely sheep, Tasmanian sheep,

mitochondrial genes (cox1, nad1, cob, rrn), are illustrated in Fig. 1

buffalo, horse, cattle, camel, pig, variant pig (or human-pig), Amer-

ican cervid, Fennoscandian cervid and lion strain. Originally, the

1.3. Subspecies strain system was based on non-genetic characters like host spec-

trum, geography, morphology and aspects of development. From

In addition to species, various subspecies of E. multilocularis and the early 1990s, gene sequence data became increasingly impor-

E. granulosus were described, mostly based on worm morphology. E. tant to define and identify the strains. Important contributions

multilocularis and E. granulosus were subsequently divided into var- to the consolidation of these infraspecific categories were the

ious subspecies, again largely based on morphological characters publications of partial sequences of the mitochondrial cox1 and

of the worms. This started in 1957, when Vogel sank E. sibiri- nad1 genes for seven strains of E. granulosus, plus E. multilocu-

censis, described only three years earlier by Rausch and Schiller, laris, E. vogeli and E. oligarthra (Bowles et al., 1992; Bowles and

as a subspecies under E. multilocularis (a third subspecies E. m. McManus, 1993a). Sequence data corresponded well to other char-

kazakhensis Shul’ts, 1962 was described from metacestodes in acters defining the strains, and led to a genotype ‘nomenclature’

ungulates) (Rausch and Schiller, 1954; Shul’ts, 1962; Vogel, 1957). (G1 to G7), partly replacing the previous strain names. Although

E. g. canadensis Webster and Cameron (1961) was erected due to only a limited number of isolates from biologically or epidemio-

host preference (reindeer) of the cyst stage. Retaining this, Sweat- logically characterised strains were genotyped, the terms ‘strain’

man and Williams added E. g. borealis (moose – canid cycle) and and ‘genotype’ were increasingly treated as synonyms. In addi-

E. g. equinus (horse – dog cycle) in addition to the nominate E. g. tion to the seven genotypes/strains that were initially characterised

granulosus from domestic sheep, cattle and pigs (Sweatman and (G1/sheep strain; G2/Tasmanian sheep strain; G3/buffalo strain;

Williams, 1963; Williams and Sweatmen, 1963). In her major tax- G4/horse strain; G5/cattle strain; G6/camel strain; G7/pig strain),

onomic revision of 1965, Verster retained the subspecies borealis over time three additional taxa were added: the American cervid

and canadensis, resurrected felidis, lycaontis and ortleppi – now strain (G8) (Bowles et al., 1994), a variant pig (or human-pig) strain

as subspecies –, described a new subspecies africanus (from cat- (G9) (Scott et al., 1997), and finally the Fennoscandian cervid strain

tle, sheep and dogs in South Africa), changed the designation of (G10) (Lavikainen et al., 2003). Lack of material for sequencing kept

Sweatman and Williams’ nominate subspecies to E. g. newzealan- the lion strain from being included in the ‘G-system’.

densis, and assigned nominate subspecies status to worm material

from Germany (from where the type species had been described) 1.5. Species, once more

(Verster, 1965). This amounted to eight subspecies of E. granulosus

(the taxa equinus, cameroni, intermedius, longimanubrius, minimus, After two decades of accumulating epidemiological, biochem-

patagonicus and oligarthra were not included in the revision). ical and geographic data on the E. granulosus strains, and

Shortly after, in his largely theoretical treatment of infraspecific cat- the phylogenetic evaluation of increasingly long mitochondrial

egories in Echinococcus, Rausch (1967) refuted the subspecies status and nuclear gene sequences (including complete mitochondrial

for sympatrical forms of E. granulosus, and attributed the mor- genomes), limitations and contradictions of the strain/genotype

phological differences found by previous authors to host-induced system within E. granulosus became apparent and called for a tax-

modifications (Rausch, 1967). A possible exception to this was seen onomic revision of the genus. Major points were (1) the apparent

in the distinction between a ‘northern form’ (or E. g. canaden- paraphyly of E. granulosus (sensu lato) with respect to E. multiloc-

sis), transmitted in wildlife cycles in North America and northern ularis and its sister taxon E. shiquicus (which had in the meantime

Eurasia, and a domestic form (E. g. granulosus), which had been been described from the Tibetan plateau; Xiao et al., 2005, 2006),

globally distributed through human activities. Yet, shortly after and (2) the fact that genetic distances between some genotypes

this consolidation, three additional species were described from (G1-3, G6-7) were in the range of microvariants of the same taxon,

South America: E. pampeanus Szidat (1967) from a wild cat species, whereas others (G4, G5) were only distantly related. After a first

E. cepanzoi Szidat (1971) (as a new name for the subspecies E. g. proposition to subdivide E. granulosus into four species (Thompson

dusicyontis Blood and Lelijveld, 1969) from a wild South Ameri- et al., 1995), E. granulosus equinus Williams and Sweatman, 1963

can canid (Lycalopex sp.), and finally E. vogeli Rausch and Bernstein was finally elevated to species rank (for the horse strain, genotype

(1972); from the bush dog (Speothos venaticus) (Blood and Lelijveld, G4), and E. ortleppi Lopez-Neyra and Soler Planas, 1943 was rein-

1969; Rausch and Bernstein, 1972; Szidat, 1967; Szidat, 1971). Of stated (for the cattle strain, genotype G5; Thompson and McManus,

these, only E. vogeli survived the test of time, while the first two 2002). This left the name E. granulosus (Batsch, 1786) for the

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

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Fig. 1. Cladogram of Echinococcus spp. obtained through Maximum Likelihood anal-

yses of 5170 nucleotides of the mitochondrial cox1, nad1, rrn and cob gene. Modified

from Hüttner et al. (2008). Fig. 2. E. granulosus sensu stricto: haplotype network of the complete mitochon-

drial cox1 gene (1608 bp). The network consists of 137 haplotypes based on 304

analysed isolates from Europe (16), western Asia (140), southern/eastern Asia (40),

genotypes G1 to G3 (sheep, Tasmanian sheep and buffalo strains), Africa (78) and South America (30) (authors, unpublished data and Genbank entries).

while the allocation of the camel, pig, cervid and lion strains was The network includes haplotypes published by Konyaev et al. (2013) and Yanagida

et al. (2012). For comparison, one isolate of E. felidis is included (Genbank accession

left unresolved until, five years later and based on the compari-

no. AB732958). The network was constructed using TCS 1.21 (Clement et al., 2000),

son of complete mitochondrial genomes, E. granulosus canadensis

with fixed connection limit at 130 steps.

Webster and Cameron, 1961 was given species status, now includ-

Circle sizes are not proportional to the haplotype frequencies. Large central cir-

ing several closely related genotypes (G6 to G10) (Nakao et al., cle: represents the most common, globally distributed haplotype (e.g. accession no.

JQ250806). Medium circles: identified haplotypes. Small circles: hypothetical inter-

2007). Finally, E. felidis Ortlepp, 1937; could be resurrected from

mediate haplotypes (not identified in this panel). Rectangle: represents 28 different

synonymy based on mitochondrial sequences obtained from pre-

haplotypes with one basepair difference to the central haplotype. Black circles: hap-

served adult worm material that had been determined by Verster in

lotypes that contain the G1 sequence of Bowles et al. (1992) (21 of 28 haplotypes

South Africa (Hüttner et al., 2008). In the current state of this (ongo- of the rectangle belong to this type). Dark grey circle: haplotypes that contain the

ing) taxonomic reshuffle, E. granulosus in its previous sense (or G2 sequence of Bowles et al. (1992). Light grey circles: haplotypes that contain the

G3 sequence of Bowles et al. (1992). White circles: not described in the G-system of

sensu lato) is split into five species (granulosus s.s., felidis, equinus,

genotypes.

ortleppi, canadensis), in addition to the agents of alveolar and poly-

cystic echinococcosis (E. multilocularis, shiquicus, oligarthra, vogeli)

(Table 2.

nad1 sequences published in the 1990s, the use of the G num-

bers has become increasingly misleading (see also discussion on

2. Species accounts and molecular epidemiology this by Nakao et al., 2013a). A substantial number of different gene

sequences have in the past been allocated to ‘G1 or ‘G3 without

2.1. Echinococcus granulosus (sensu stricto) a clear definition. The problem of allocating haplotypes based on

longer (or other) genome fragments is illustrated in Fig. 2. Using the

The type specimen of E. granulosus originated from a sheep, and complete sequence of the mitochondrial cox1 gene, 137 haplotypes

it is likely that it belonged to what was later known as the ‘sheep where identified among 304 isolates of the G1-3 cluster from west-

strain’ (this is less clear for Verster’s subspecies E. g. granulosus, as ern, eastern and southern Asia, Europe, Africa and South America.

the worms used for the description originated from a pig cyst). In Using the original G-definition of cox1 (366 bp sequences), a large

the current concept, this name is reserved for the ‘sheep strain’, proportion of the haplotypes are not homologous with either G1, 2

‘Tasmanian sheep strain’ and ‘buffalo strain’ (which correspond to or 3, although they clearly belong to the same cluster. Any haplo-

the genotypes G1, G2 and G3, respectively), as well as a large num- type in this cluster is removed from any other by no more than 20 bp

ber of other closely related variants. It was already apparent from steps, while the cluster as a whole has a distance of >100 bp from

the analysis of relatively short gene sequences (Bowles et al., 1992; the sister species E. felidis. The use of E. granulosus (s.s.) as a name

Bowles et al., 1992a), that G1-3 were much more closely related for this cluster would therefore appear to be the most reasonable

to each other than to any other known genotype. This was con- approach. If subdivisions of this taxon should become necessary,

firmed by more recent studies using longer sequences and/or other they will have to be based on convincing additional information

genes, which also identified a large number of additional haplo- concerning biological characteristics (host affinities, morphology)

types belonging to this cluster (Busi et al., 2007; Casulli et al., 2012; and nuclear sequence data.

Nakao et al., 2013a; Snabel et al., 2009; Vural et al., 2008; Yanagida Globally, the principal intermediate hosts for this taxon are

et al., 2012). In view of this, and regarding the fact that, strictly sheep, although fertile infections have been recorded from a wide

speaking, the ‘G-nomenclature’ is defined by the short cox1 and range of livestock and herbivorous wildlife species worldwide,

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

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including equids (Cardona and Carmena, 2013; Thompson and lations of eastern and southern Africa, respectively (Kagendo et al.,

McManus, 2001). Cattle are frequently infected with this taxon 2014; Wassermann et al., 2015).

in many parts of the world, but they seem to contribute little

to the transmission as the majority of cysts do not reach fertil- 2.3. Echinococcus equinus

ity (McManus and Thompson, 2003). E. granulosus s.s. is the most

frequent agent of human cystic echinococcosis worldwide: 88% of Williams and Sweatman (1963) characterised E. granulosus

1661 genotyped human isolates belonged to this species (Alvarez worms derived from horse cysts in Britain and suggested they rep-

Rojas et al., 2014). Exceptions are only countries where E. granulo- resent a distinct subspecies, E. granulosus equinus. Subsequently,

sus s.s. is absent or rare in animals in favour of other Echinococcus other studies confirmed biological differences between horse-

spp., as is the case in Sudan and Egypt (Khalifa et al., 2014; Omer derived E. granulosus and isolates originating from other host

et al., 2011). Cysts are often fertile in humans, and numerous obser- species (Kumaratilake et al., 1986; Smyth, 1977). Based on partial

vations indicate that the high number of cases may be due to sequence of the cox1 gene, the G4 genotype was characterised from

increased infectivity (or pathogenicity) of E. granulosus s.s. com- two cyst isolates from horses (UK and Spain) and one from a don-

pared to other Echinococcus species. Although the typical lifecycle key (Ireland) (Bowles et al., 1992). Species rank was suggested by

patterns involve livestock and domestic dogs, E. granulosus s.s. is Thompson and McManus (2002), and today it is firmly established

also known from wild carnivores in eastern Europe and (probably) as an independent species, E. equinus. It seems to be a highly specific

Iran (Beiromvand et al., 2011; Breyer et al., 2004) and from wild parasite of Equidae (horses, donkeys and zebras) as intermediate

sheep in Turkey (Simsek and Eroksuz, 2009), possibly as a spill- hosts, although it was recently recorded from a captive lemur in

over from domestic transmission. Whether the latter also holds true the UK (Boufana et al., 2012).

for recent records in lions, spotted hyenas and wildebeests in con- As cysts in horses – which have been recorded from all over the

servation areas of Kenya, remains to be confirmed (Kagendo et al., world – may also belong to other Echinococcus spp. (Boufana et al.,

2014). In any case, there is now a surprising number of records from 2014; Varcasia et al., 2008), molecular confirmation is necessary.

wild carnivores of eastern Africa. These may not only contribute to Thus, E. equinus has only been confirmed for the United Kingdom,

the lifecycle in the livestock-wildlife interface near conservation Ireland, Germany, Italy, Spain, Tunisia and Egypt (Aboelhadid et al.,

areas, but also as scavengers of livestock carcasses in areas that 2013; Blutke et al., 2010; Mwambete et al., 2004; Smyth, 1977).

are now depleted of large wild herbivores, e.g. golden and black- However, its occurrence in other regions is highly likely, e.g. eastern

backed jackals in northwestern Kenya (Macpherson and Wachira, Europe and South Africa, where undetermined Echinococcus cysts

1997). Regional differences in haplotype diversity led to a hypoth- are known from horses, donkeys and zebras. Recently a wildlife

esis on the origin of E. granulosus s.s. in a wildlife cycle in western cycle of E. equinus was discovered in the Etosha National Park of

Asia and its subsequent spread to other regions in the wake of live- Namibia between lions and black-backed jackals as definitive hosts,

stock domestication. Compared with a centre of high diversity in and plains zebras as intermediate hosts (Wassermann et al., 2015);

western Asia and the Middle East, the complexity of haplotype net- morphological observations and transmission studies suggest that

works decreases toward Europe and eastern Asia and appears to be this cycle may be widespread in southern Africa (Macpherson and

particularly low in South America (Casulli et al., 2012; Yanagida Wachira, 1997).

et al., 2012).

2.4. Echinococcus ortleppi

2.2. Echinococcus felidis

The original description is based on adult worms from dogs of

The species was originally described from lions of the Transvaal the Transvaal region of South Africa, which had been initially identi-

region of South Africa. Even after the synonymisations by Rausch fied as E. granulosus (Ortlepp, 1934). Only later were they described

and Nelson (1963) and Rausch (1967), it was tentatively retained as a new species for morphological differences (Lopez-Neyra and

as a separate taxon (as subspecies E. g. felidis or, later, as the ‘lion Soler Planas, 1943). Worms from dogs and jackals, that had been

strain’). This was mainly based on the suitability of a member of experimentally infected with cysts originating from cattle of the

the cat family as host for the adult stage, which was thought at the Transvaal, were later allocated to the same taxon, now named E.

time to be an unusual feature for E. granulosus. Recent molecular granulosus ortleppi (Verster, 1965). Later known as the cattle strain

characterisation of material from Ugandan lions and preserved ‘his- of E. granulosus, it was shown that it differed from other taxa in

torical’ worm specimens from South Africa showed, that this taxon a number of characters, e.g. by cysts typically reaching fertility in

belongs to the same clade as E. granulosus s.s., but is sufficiently cattle, morphological details of the adult worms, and a particularly

distinct to deserve species status (Fig. 1) (Hüttner et al., 2008). As short development time in dogs (Thompson et al., 1984). Apart from

shown in the haplotype network of the mitochondrial cox1 gene, South Africa, where it was believed to be frequent in the cattle-

it is removed from the E. granulosus s.s. cluster by more than 100 raising region of Transvaal (Verster, 1965), it was later reported

hypothetical base pair exchanges (Fig. 2). from Switzerland and Germany (Thompson et al., 1984; Worbes

By now, molecularly confirmed isolates of E. felidis are known et al., 1989). Bowles et al. (1992) characterised the partial cox1

from lions and spotted hyenas in Uganda, Kenya and South Africa; sequence from a bovine from the Netherlands, and designated it as

the only confirmed intermediate host record is from a Ugandan the G5 genotype. Under the resurrected name E. ortleppi (Thompson

warthog (Hüttner et al., 2008; Hüttner and Romig, 2009; Hüttner and McManus, 2002), it is now considered as a separate species,

et al., 2009). Other than this, the host range (including human belonging to the same clade as E. canadensis (Fig. 1) (Nakao et al.,

pathogenicity) is unknown; it had not been found in 353 wilde- 2013b).

beest (Connochaetes mearnsi) in the Masai Mara conservation area E. ortleppi seems to be well adapted to cattle as intermediate

of Kenya, although it is widespread there in carnivores. Likewise, it hosts, although it can also reach fertility in other species. Fertile

was not present among 279 genotyped Echinococcus cysts recov- cysts in cattle from central European countries were common as

ered from livestock from the vicinity of Kenyan national parks recently as the 1980s (Hahn et al., 1986), but the parasite is now

(Addy et al., 2012). While E. felidis has not yet been found in any either extinct there or occurs only sporadically (Romig et al., 2006).

canid, the susceptibility of lions as definitive hosts is not a distin- Elsewhere, it seems to be widespread, but usually rare (Cardona and

guishing feature for this taxon. In recent studies, E. granulosus s.s. Carmena, 2013). A small number of infections have been molec-

and E. equinus were shown to be regular parasites in wild lion popu- ularly identified from cattle in Sudan (Dinkel et al., 2004; Omer

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

Parasitol. (2015), http://dx.doi.org/10.1016/j.vetpar.2015.07.035

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6 T. Romig et al. / Veterinary Parasitology xxx (2015) xxx–xxx

et al., 2010), Kenya (Mbaya et al., 2014), South Africa (Mogoye et al., vs. E. canadensis (G8, G10) taxonomically impossible, unless con-

2013), Brazil (de la Rue et al., 2006), Italy (Busi et al., 2007) and most tradicting results will become available from relevant parts of the

recently in France (Grenouillet et al., 2014), cattle and buffaloes in nuclear genome (Lavikainen et al., 2006; Moks et al., 2008; Nakao

India (Zhang et al., 1999), goats and sheep in Kenya (Mbaya et al., et al., 2013b). Most recently, a valid case was made to resolve this

2014), and pigs in Kenya and India (Dinkel et al., 2004; Pednekar cluster into three species: E. intermedius (G6/7), E. borealis (G8)

et al., 2009). A case of monkey infection with E. ortleppi has been and E. canadensis (G 10) (Lymbery et al., 2015). This split is con-

reported from Vietnam (Plesker et al., 2009), and a captive deer sistent with the mitochondrial phylogeny, and may in future lead

imported from France into the UK was found infected (Boufana to a more stable nomenclature. Yet, from a more conservative point

et al., 2012). Only seven human cases of E. ortleppi infection are of view, there is still a number of open issues. They mainly concern

known from various parts of the world (Argentina, Brazil, India, the maintenance of the proposed species’ genetic identity in sym-

Mexico, Netherlands and South Africa) (Alvarez Rojas et al., 2014). patric situations, which is crucial when independent evolutionary

Given the ubiquitous presence of cattle and dogs as suitable hosts, fates of the three lineages are proposed. To confirm this, the exist-

the rarity of this parasite is perplexing. It may be explained by the ing (mainly mitochondrial) data appear inadequate, and more data

fact, that, even in traditional pastoral societies, cattle are mostly on nuclear gene loci will be needed from a significant number of

sold alive and slaughtered in distant locations, so transmission to geographically spaced isolates, in addition to more comprehensive

the local dog population is inhibited (Addy et al., 2012). information on biological and morphological features (Nakao et al.,

2013a; Nakao et al., 2013b). Molecular distinction between G6 and

2.5. Echinococcus canadensis G7 rests on minor differences. The pairwise divergence value of two

mitochondrial genes (>2600 bp) was much lower between G6 and

As defined here, the species includes the pig, camel and cervid G7 isolates than between geographical variants of E. multilocularis,

strains. Adult worms derived from cysts of camel and pig origin which makes it doubtful to address these two strains as sepa-

were shown to differ in various morphological characters from rate entities. As some isolates cannot be clearly allocated to either

those of other strains, and show similarity to each other (Eckert of them, members of this cluster have been referred to as G6/7

et al., 1989; Eckert et al., 1993; Lymbery et al., 2015). This sup- (Mogoye et al., 2013; Nakao et al., 2013a; Nakao et al., 2013b). Still,

ported propositions of a specific camel strain (for the Middle East biologically relevant variants may exist within the G6/7 cluster: in

and eastern Africa), and of a pig strain (for Eastern Europe and the Neuquén province of Argentina goats were found infected with

Mexico). In addition, based on epidemiological and phenotypic G6, while pigs were infected with G7 (Soriano et al., 2010). This may

features, the ‘northern biotype’ of E. granulosus, transmitted in or may not be significant (e.g., G7 is common in goats in Greece —

a reindeer/moose—wolf/dog cycle, was tentatively allocated to a Varcasia et al., 2007), but in any case there is a need to investigate

cervid strain (Thompson et al., 1995). The evidence for uniting pig, the intraspecific genetic diversity of E. canadensis (including nuclear

camel and cervid strains in a single species derived from molec- genes) and link it to epidemiologically relevant data. In the mean-

ular sequence data. Cysts from African camels and goats, Polish time, not to lose valuable information, it is important to maintain

pigs and North American moose were molecularly characterised the provisional subdivision of E. canadensis into the four genotypes

as genotypes G6, G7 and G8 (Bowles et al., 1992, 1994; Bowles when conducting molecular surveys or isolate identification (Nakao

and McManus, 1993b) which was later followed by genotype G9 et al., 2013a).

from a human patient of Poland (Scott et al., 1997), and G10 for It had been suggested that the genotypes of E. canadensis are

the ‘Fennoscandian’ cervid strain (Lavikainen et al., 2003). While of minor relevance for human health, because case numbers are

G9, which had been based on ITS1-RFLP patterns, is now thought usually low in regions where these taxa predominate (e.g. Eastern

to represent a microvariant of G7, the other four genotypes were Europe, Sudan/Egypt, northern parts of Eurasia and North Amer-

shown in various phylogenetic studies to form a closely related ica) and some case reports indicated a benign course of disease

clade, with E. ortleppi as a sister taxon (Fig. 1) (Bowles et al., 1995; (Wilson et al., 1968). Also, in areas of East Africa, where both E.

Lavikainen et al., 2006, 2003; Lymbery et al., 2015). Following a canadensis (G6) and E. granulosus s.s. are frequent in animals, only

comparison of complete mitochondrial genomes, the unification of a small proportion of patients were found infected with the former

these strains as E. canadensis was proposed (Nakao et al., 2007). The species (Romig et al., 2011); a similar situation seems to prevail

name derived from the subspecies E. granulosus canadensis Webster in North Africa and the Middle East (Alvarez Rojas et al., 2014).

and Cameron, 1961 described from reindeer and dogs in Canada. Yet, the contribution to global disease load is not negligible, as in

The name had been tentatively retained by Rausch (1967) as an a worldwide conspectus of 1661 human cases, 184 (11.07%) were

alternative name for the ‘northern biotype’ of E. granulosus, while caused by G6 or G7 (only two cases by G8 or G10). In some coun-

the only other scientific name that can be clearly linked to any of tries E. canadensis is even the predominant cause of human cystic

these strains, E. g. borealis Sweatman and Williams, 1963 was con- echinococcosis, like Sudan, Egypt, Poland and Austria (Aaty et al.,

sidered a junior synonym. Differences in host range and geography 2012; Omer et al., 2010; Pawlowski and Stefaniak, 2003; Schneider

between the sylvatic (or semi-domestic) cervid strains (G8/G10) et al., 2008, 2010); it is important to note, however, that in these

and the domestic camel and pig strains (G6/G7) had led to the pro- countries E. granulosus s.s. is absent or rare also in animals. Human

posal to regard the latter as a separate species, and the name E. cystic echinococcosis in North America of undetermined origin (G8

intermedius has been suggested (Sharma et al., 2013; Thompson, or G10?) was characterised by a benign course of disease (Wilson

2008). However, the morphological data (and the illustrations) et al., 1968) and cysts of E. canadensis G7 were found to be smaller

from the original description of E. intermedius (based on two worms and more frequently asymptomatic compared to those caused by E.

of a Spanish dog — Lopez-Neyra and Soler Planas, 1943) do not granulosus s.s. (Schneider et al., 2010). However, aggressive disease

fully agree with descriptions of worms belonging to the camel and was reported from a case with confirmed G8 infection (McManus

pig strains (Eckert et al., 1989; Eckert et al., 1993). The ecological et al., 2002), and recently an affinity of E. canadensis G6 for the

and geographic distinction between the ‘domestic’ G6/7 and the brain was suggested (Sadjjadi et al., 2013). Geographically, the G6/7

‘sylvatic’ G8 and G10 has become blurred since G6 was recently cluster is spread worldwide with the exception of Australia, east-

found in wolves and reindeer in the Altai region and Yakutia, Rus- ern Asia and North America; the numerous records of molecularly

sia (Konyaev et al., 2013). In addition, considering the existing data characterised isolates in livestock have been recently reviewed

on mitochondrial sequences, G10 is much more closely related to (Cardona and Carmena, 2013). In general, pigs (including wild boar)

G6/7 than to G8, which makes a split into E. intermedius (G6, G7) and camelids are suitable hosts and frequently contain fertile cysts.

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

Parasitol. (2015), http://dx.doi.org/10.1016/j.vetpar.2015.07.035

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In the absence of pigs and camels, goats may also perpetuate the certainty and is lost for retrospective analysis. In this light it is

lifecycle, while sheep and cattle are rarely infected and cysts are important to remind veterinarians, members of the medical pro-

often sterile. Cases of wildlife involvement are known from Europe fessions and biologists to apply appropriate and specific diagnostic

(wolf, wild boar) and Siberia (wolf, reindeer) (Daniel Mwambete procedures when conducting studies on cystic echinococcosis, so

et al., 2004; Dinkel et al., 2004; Guerra et al., 2013; Konyaev et al., that the causative organisms are clearly defined and the data can

2013; Umhang et al., 2014). Both ‘cervid strains’ (G8 and G10) contribute to gradually close our gaps of knowledge.

are sympatrically distributed in the temperate to arctic regions of

the northern hemisphere. Reports on possible differences in host

spectrum or other biologically relevant features between these Acknowledgements

genotypes are inconclusive due to paucity of data. Both G8 and G10

have been reported from wolf—moose lifecycles, with wapiti as an We thank Mar Siles-Lucas (Salamanca) for her help with liter-

additional host for G8 in North America. G10 has also been found in ature, and we gratefully acknowledge financial support through

(semi-) domesticated reindeer, and this strain is possibly respon- the CESSARi network (Cystic Echinococcosis in sub-Saharan Africa

sible for the frequent cases in reindeer and humans, which had Research Initiative), funded by the Deutsche Forschungsgemein-

formerly been reported from northern Fennoscandia (Lavikainen schaft (RO 3753/1-1, 2-1).

et al., 2006; Moks et al., 2008; Schurer et al., 2013; Thompson et al.,

2006; Oksanen and Lavikainen, 2015).

References

Aaty, H.E., Abdel-Hameed, D.M., Alam-Eldin, Y.H., El-Shennawy, S.F., Aminou, H.A.,

3. Conclusion

Makled, S.S., Darweesh, S.K., 2012. Molecular genotyping of Echinococcus

granulosus in and human isolates from Egypt. Acta Trop. 121, 125–128.

Aboelhadid, S.M., El-Dakhly, K.M., Yanai, T., Fukushi, H., Hassanin, K.M., 2013.

The current taxonomic concept for Echinococcus results from

Molecular characterization of Echinococcus granulosus in Egyptian donkeys.

critical evaluation of the biological and molecular data, which are

Vet. Parasitol. 193, 292–296.

available at this time. It provides an appropriate basis for further Abuladze, K.I., 1964. TAENIATA of animals and man and diseases cause by them. In:

Skrjabin, A.K.I. (Ed.), Essentials of Cestodology, Volume IV. srael Program for

research by recognising distantly related taxa (cryptic species) of

Scientific Translations, 1970, Jerusalem.

the E. granulosus (sensu lato) assemblage as individual species and

Addy, F., Alakonya, A., Wamae, N., Magambo, J., Mbae, C., Mulinge, E., Zeyhle, E.,

by uniting closely related strains and genotypes under common Wassermann, M., Kern, P., Romig, T., 2012. Prevalence and diversity of cystic

species names. However, a number of taxonomic issues are still echinococcosis in livestock in Maasailand, Kenya. Parasitol. Res. 111,

2289–2294.

unresolved and require additional data. This concerns the corre-

Alvarez Rojas, C., Romig, T., Lightowlers, M.W., 2014. Echinococcus granulosus sensu

lation of molecular markers with morphological features (e.g. as

lato genotypes infecting humans—review of current knowledge. Int. J.

a possible alternative identification method). A large body of – Parasitol. 44, 9–18.

Beiromvand, M., Akhlaghi, L., Fattahi Massom, S.H., Mobedi, I., Meamar, A.R.,

mostly older – literature data on morphological features of adult

Oormazdi, H., Motevalian, A., Razmjou, E., 2011. Detection of Echinococcus

worms is available, but none of the descriptions (with the excep-

multilocularis in carnivores in Razavi Khorasan province, Iran using

tion of E. felidis) can be conclusively correlated to genetic markers mitochondrial DNA. PLoS Negl. Trop. Dis. 5, e1379.

Beveridge, I., 1974. Aspects of the taxonomy of the genus Taenia L. 1758. University

which are now used for species identification. This is mainly due

of Melbourne, Ph D Thesis.

to the lack of type material, storage of original material in formalin

Blood, B.D., Lelijveld, J.L., 1969. Studies on sylvatic echinococcosis in southern

with subsequent DNA degradation and prohibitive efforts, which South America. Z. Tropenmed. Parasite 20, 475–482.

Blutke, A., Hamel, D., Hüttner, M., Gehlen, H., Romig, T., Pfister, K., Hermanns, W.,

are now required to conduct transmission experiments. Still, cor-

2010. Cystic echinococcosis due to Echinococcus equinus in a horse from

relative data between morphology and gene sequences are a matter

southern Germany. J. Vet. Diagn. Invest. 22, 458–462.

of taxonomic priority and would make a large number of histori- Boufana, B., Lahmar, S., Rebai, W., Ben Safta, Z., Jebabli, L., Ammar, A., Kachti, M.,

Aouadi, S., Craig, P.S., 2014. Genetic variability and haplotypes of Echinococcus

cal data accessible for epidemiological reappraisal. In addition, the

isolates from Tunisia. Trans. R. Soc. Trop. Med. Hyg. 108, 706–714.

extent and phylogenetic relevance of interbreeding among species

Boufana, B., Stidworthy, M.F., Bell, S., Chantrey, J., Masters, N., Unwin, S., Wood, R.,

is unclear, because most recent studies focused on mitochondrial Lawrence, R.P., Potter, A., McGarry, J., Redrobe, S., Killick, R., Foster, A.P.,

sequences, which are not subject to recombination. Differences Mitchell, S., Greenwood, A.G., Sako, Y., Nakao, M., Ito, A., Wyatt, K., Lord, B.,

Craig, P.S., 2012. Echinococcus and Taenia spp. from captive mammals in the

between the phylogenies of nuclear and mitochondrial genomes

United Kingdom. Vet. Parasitol. 190, 95–103.

(e.g. by the replacement of nuclear genes due to male introgres-

Bowles, J., Blair, D., McManus, D.P., 1992. Genetic variants within the genus

sion) could explain biological differences between isolates of the Echinococcus identified by mitochondrial DNA sequencing. Mol. Biochem.

Parasitol. 54, 165–173.

same or closely related mitochondrial genotypes. In addition, the

Bowles, J., Blair, D., McManus, D.P., 1994. Molecular genetic characterization of the

extent of intraspecific diversity is insufficiently known, particularly

cervid strain (‘northern form’) of Echinococcus granulosus. Parasitology 109,

within E. canadensis. Despite this, the increased awareness for the 215–221.

Bowles, J., Blair, D., McManus, D.P., 1995. A molecular phylogeny of the genus

diversity of the agents of cystic echinococcosis – now emphasised

Echinococcus. Parasitology 110 (Pt 3), 317–328.

by species names rather that genotype numbers – has already led

Bowles, J., McManus, D.P., 1993a. Molecular variation in Echinococcus. Acta Trop.

to an impressive number of recent studies on geographical spread, 53, 291–305.

Bowles, J., McManus, D.P., 1993b. NADH dehydrogenase 1 gene sequences

host range and impact on human health of the various species. It is

compared for species and strains of the genus Echinococcus. Int. J. Parasitol. 23,

already apparent, that they are distinct from each other to an extent 969–972.

that is not only biologically interesting, but also highly relevant for Breyer, I., Georgieva, D., Kurdova, R., Gottstein, B., 2004. Echinococcus granulosus

strain typing in Bulgaria: the G1 genotype is predominant in intermediate and

medical and veterinary practitioners. This includes differences in

definitive wild hosts. Parasitol. Res. 93, 127–130.

host specificity, but also possibly diverging parameters of diagnos-

Brumpt, E., Joyeux, C., 1924. Description d’un nouvel echinocoque: Echinococcus

tic tests, different responses to vaccines and, importantly, possibly cruzi n. sp. Ann. Parasitol. Hum. Comp. 3, 226–231.

required modifications of clinical management due to differences Busi, M., Snabel, V., Varcasia, A., Garippa, G., Perrone, V., De Liberato, C., D’Amelio,

S., 2007. Genetic variation within and between G1 and G3 genotypes of

in pathogenicity or response to drugs. Unfortunately, even though

Echinococcus granulosus in Italy revealed by multilocus DNA sequencing. Vet.

this variability has been recognised for a long time, a large number

Parasitol. 150, 75–83.

of epidemiological and clinical data (in particular from the largest Cameron, T.W.M., 1926. Observation on the genus Echinococcus Rudolphi, 1801. IV.

J. Helminthol., 13–22.

part of the 20th century) have been published summarily under the

Cardona, G.A., Carmena, D., 2013. A review of the global prevalence, molecular

name ‘E. granulosus’. Unless voucher specimens have been kept,

epidemiology and economics of cystic echinococcosis in production animals.

a large part of this information can now not be interpreted with Vet. Parasitol. 192, 10–32.

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

Parasitol. (2015), http://dx.doi.org/10.1016/j.vetpar.2015.07.035

G Model

VETPAR-7722; No. of Pages 9 ARTICLE IN PRESS

8 T. Romig et al. / Veterinary Parasitology xxx (2015) xxx–xxx

Casulli, A., Interisano, M., Sreter, T., Chitimia, L., Kirkova, Z., La Rosa, G., Pozio, E., Mogoye, B.K., Menezes, C.N., Wong, M.L., Stacey, S., von Delft, D., Wahlers, K.,

2012. Genetic variability of Echinococcus granulosus sensu stricto in Europe Wassermann, M., Romig, T., Kern, P., Grobusch, M.P., Frean, J., 2013. First

inferred by mitochondrial DNA sequences. Infect. Genet. Evol. 12, 377–383. insights into species and genotypes of Echinococcus in South Africa. Vet.

Clement, M., Posada, D., Crandall, K.A., 2000. TCS: a computer prgram to estimate Parasitol. 196, 427–432.

gene genealogies. Mol. Ecol. 9, 1657–1659. Moks, E., Jogisalu, I., Valdmann, H., Saarma, U., 2008. First report of Echinococcus

Daniel Mwambete, K., Ponce-Gordo, F., Cuesta-Bandera, C., 2004. Genetic granulosus G8 in Eurasia and a reappraisal of the phylogenetic relationships of

identification and host range of the Spanish strains of Echinococcus granulosus. ‘genotypes’ G5-G10. Parasitology 135, 647–654.

Acta Trop. 91, 87–93. Mwambete, D.K., Ponce-Gordo, F., Cuesta-Bandera, C., 2004. Genetic identification

de la Rue, M.L., Dinkel, A., Mackenstedt, U., Romig, T., 2006. New data on and host range of the Spanish strains of Echinococcus granulosus. Acta Trop. 91,

Echinococcus spp. in Southern Brazil. Rev. Inst. Med. Trop. Sao. Paulo 48, 87–93.

103–104. Nakao, M., Lavikainen, A., Yanagida, T., Ito, A., 2013a. Phylogenetic systematics of

Diesing, K.M., 1863. Revision der Cephalocotyteen. Abteilung: Paramecocotyleen. the genus Echinococcus (: ). Int. J. Parasitol. 43, 1017–1029.

Sitzungsb. K. Akad. Wissensch. Wien Math-Naturw. 48. Nakao, M., McManus, D.P., Schantz, P.M., Craig, P.S., Ito, A., 2007. A molecular

Dinkel, A., Njoroge, E.M., Zimmermann, A., Wälz, M., Zeyhle, E., Elmahdi, I.E., phylogeny of the genus Echinococcus inferred from complete mitochondrial

Mackenstedt, U., Romig, T., 2004. A PCR system for detection of species and genomes. Parasitology 134, 713–722.

genotypes of the Echinococcus granulosus-complex, with reference to the Nakao, M., Yanagida, T., Konyaev, S., Lavikainen, A., Odnokurtsev, V.A., Zaikov, V.A.,

epidemiological situation in eastern Africa. Int. J. Parasitol. 34, 645–653. Ito, A., 2013b. Mitochondrial phylogeny of the genus Echinococcus (Cestoda:

Eckert, J., Thompson, R.C., Lymbery, A.J., Pawlowski, Z.S., Gottstein, B., Morgan, Taeniidae) with emphasis on relationships among Echinococcus canadensis

U.M., 1993. Further evidence for the occurrence of a distinct strain of genotypes. Parasitology 140, 1625–1636.

Echinococcus granulosus in European pigs. Parasitol. Res. 79, 42–48. Omer, R.A., Daugschies, A., Romig, T., 2011. Cystic echinococcosis in Sudan and

Eckert, J., Thompson, R.C., Michael, S.A., Kumaratilake, L.M., el-Sawah, H.M., 1989. South Sudan: research history of a neglected zoonosis. Berl. Munch. Tierarztl.

Echinococcus granulosus of camel origin: development in dogs and parasite Wochenschr. 124, 521–527.

morphology. Parasitol. Res. 75, 536–544. Omer, R.A., Dinkel, A., Romig, T., Mackenstedt, U., Elnahas, A.A., Aradaib, I.E.,

Grenouillet, F., Umhang, G., Arbez-Gindre, F., Mantion, G., Delabrousse, E., Millon, Ahmed, M.E., Elmalik, K.H., Adam, A., 2010. A molecular survey of cystic

L., Boué, F., 2014 Dec. Echinococcus ortleppi infections in humans and cattle, echinococcosis in Sudan. Vet. Parasitol. 169, 340–346.

France. Emerg. Infect. Dis. 20, in press. Ortlepp, J.R., 1934. Echinococcus in dogs from Pretoria and vicinity. Onderstepoort

Guerra, D., Armua-Fernandez, M.T., Silva, M., Bravo, I., Santos, N., Deplazes, P., J. Vet. Sci. Anim. Ind. 3, 97–108.

Madeira de Carvalho, L.M., 2013. Taeniid species of the Iberian wolf (Canis Ortlepp, J.R., 1937. South African Helminths—Part I. Onderstepoort J. Vet. Sci. Anim.

lupus signatus) in Portugal with special focus on Echinococcus spp. Int. J. Ind. 9, 311–336.

Parasitol. Parasites Wildl. 2, 50–53. Oksanen, A., Lavikainen, A., 2015. Host ecology and Echinoccoccus canadensis

Hahn, E., Kuske, V., Hörchner, F., Reuter, G., 1986. Zur Verbreitung der zystischen transmission in the North. Vet. Parasitol.

Echinokokkose beim Rind in Deutschland. Dtsch. Tierarztl. Wochenschr. 93, Pawlowski, Z., Stefaniak, J., 2003. The pig strain of Echinococcus granulosus in

445–447. humans: a neglected issue. Trends Parasitol. 19, 439.

Hüttner, M., Nakao, M., Wassermann, T., Siefert, L., Boomker, J.D., Dinkel, A., Sako, Pednekar, R.P., Gatne, M.L., Thompson, R.C., Traub, R.J., 2009. Molecular and

Y., Mackenstedt, U., Romig, T., Ito, A., 2008. Genetic characterization and morphological characterisation of Echinococcus from food producing animals

phylogenetic position of Echinococcus felidis (Cestoda: Taeniidae) from the in India. Vet. Parasitol. 165, 58–65.

African lion. Int. J. Parasitol. 38, 861–868. Plesker, R., Nadler, T., Dinkel, A., Romig, T., 2009. A case of an Echinococcus ortleppi

Hüttner, M., Romig, T., 2009. Echinococcus species in African wildlife. Parasitology infestation in a red-shanked douc langur (Pygathrix nemaeus) in northern

136, 1089–1095. Vietnam. Vietnamese J. Primatol. 3, 75–81.

Hüttner, M., Siefert, L., Mackenstedt, U., Romig, T., 2009. A survey of Echinococcus Rausch, R.L., 1967. A consideration of infraspecific categories in the genus

species in wild carnivores and livestock in East Africa. Int. J. Parasitol. 39, Echinococcus Rudolphi, 1801 (Cestoda: Taeniidae). J. Parasitol. 53, 484–491.

1269–1276. Rausch, R.L., Bernstein, J.J., 1972. Echinococcus vogeli spp. n. (Cestoda: Taeniidae)

Kagendo, D., Magambo, J.K., Agola, E.L., Njenga, S.M., Zeyhle, E., Kakundi, E.M., from the bush dog, Speothos venaticus (Lund.). Z. Tropenmed. Parasite 23,

Njeru, P.G., Mbae, C., Muchiri, E.M., Wassermann, M., Kern, P., Romig, T., 2014. 25–34.

A survey for Echinococcus spp. of carnivores in six wildlife conservation areas Rausch, R.L., Nelson, G.S., 1963. A review of the genus Echinococcus Rudolphi 1801.

in Kenya. Parasitol. Int. 63, 604–611. Ann. Trop. Med. Parasitol. 57, 127–135.

Khalifa, N.O., Khater, H.F., Fahmy, H.A., Radwan, M.E.I., Afify, J.S.A., 2014. Rausch, R.L., Schiller, E.L., 1954. Studies on the helminth fauna of Alaska. 24.

Genotyping and phylogenetic analysis of cystic echinococcosis isolated from Echinococcus sibiricensis n. sp. from St. Lawrence Island. J. Parasitol. 40,

camels and humans in Egypt. Am. J. Epidemiol. Inf. Dis. 2, 74–82. 659–662.

Konyaev, S.V., Yanagida, T., Nakao, M., Ingovatova, G.M., Shoykhet, Y.N., Bondarev, Romig, T., Dinkel, A., Mackenstedt, U., 2006. The present situation of

A.Y., Odnokurtsev, V.A., Loskutova, K.S., Lukmanova, G.I., Dokuchaev, N.E., echinococcosis in Europe. Parasitol. Int. 55 (Suppl), S187–S191.

Spiridonov, S., Alshinecky, M.V., Sivkova, T.N., Andreyanov, O.N., Abramov, S.A., Romig, T., Omer, R.A., Zeyhle, E., Huttner, M., Dinkel, A., Siefert, L., Elmahdi, I.E.,

Krivopalov, A.V., Karpenko, S.V., Lopatina, N.V., Dupal, T.A., Sako, Y., Ito, A., Magambo, J., Ocaido, M., Menezes, C.N., Ahmed, M.E., Mbae, C., Grobusch, M.P.,

2013. Genetic diversity of Echinococcus spp. in Russia. Parasitology 140, Kern, P., 2011. Echinococcosis in sub-Saharan Africa: emerging complexity.

1637–1647. Vet. Parasitol. 181, 43–47.

Kumaratilake, L.M., Thompson, R.C., 1982. A review of the taxonomy and speciation Sadjjadi, S.M., Mikaeili, F., Karamian, M., Maraghi, S., Sadjjadi, F.S.,

of the genus Echinococcus Rudolphi 1801. Z. Parasitenkd. 68, 121–146. Shariat-Torbaghan, S., Kia, E.B., 2013. Evidence that the Echinococcus granulosus

Kumaratilake, L.M., Thompson, R.C., Eckert, J., 1986. Echinococcus granulosus of G6 genotype has an affinity for the brain in humans. Int. J. Parasitol. 43,

equine origin from different countries possess uniform morphological 875–877.

characteristics. Int. J. Parasitol. 16, 529–540. Schantz, P.M., Colli, C., Cruz-Reyes, A., Prezioso, U., 1976. Sylvatic echinococcosis in

Lavikainen, A., Lehtinen, M.J., Laaksonen, S., Agren, E., Oksanen, A., Meri, S., 2006. Argentina. 2. Susceptibility of wild carnivores to Echinococcus granulosus

Molecular characterization of Echinococcus isolates of cervid origin from (Batsch 1786) and hostinduced morphological variation. Tropenmed. Parasitol.

Finland and Sweden. Parasitology 133, 565–570. 27, 70–78.

Lavikainen, A., Lehtinen, M.J., Meri, T., Hirvela-Koski, V., Meri, S., 2003. Molecular Schneider, R., Gollackner, B., Edel, B., Schmid, K., Wrba, F., Tucek, G., Walochnik, J.,

genetic characterization of the Fennoscandian cervid strain, a new genotypic Auer, H., 2008. Development of a new PCR protocol for the detection of species

group (G10) of Echinococcus granulosus. Parasitology 127, 207–215. and genotypes (strains) of Echinococcus in formalin-fixed, paraffin-embedded

Lopez-Neyra, C.R., Soler Planas, M.A., 1943. Revision del genero Echinococcus Rud tissues. Int. J. Parasitol. 38, 1065–1071.

y description de una especie nuéva Parasita intestinal del porro en Almeria. Schneider, R., Gollackner, B., Schindl, M., Tucek, G., Auer, H., 2010. Echinococcus

Rev. Iber. Parasitol. 3, 169–194. canadensis G7 (pig strain): an underestimated cause of cystic echinococcosis in

Lymbery, A.J., Jenkins, E.J., Schurer, J.M., Thompson, R.C.A., 2015. Echinococcus Austria. Am. J. Trop. Med. Hyg. 82, 871–874.

canadensis, E. borealis and E. intermedius. What’s in a name? Trends Parasitol. Schurer, J., Shury, T., Leighton, F., Jenkins, E., 2013. Surveillance for Echinococcus

31, 23–29. canadensis genotypes in Canadian ungulates. Int. J. Parasitol. Parasites Wildl. 2,

Macpherson, C.N.L., Wachira, T.M., 1997. Cystic echinococcosis in Africa south of 97–101.

the Sahara. In: Andersen, F.L., Ouhelli, H., Kachani, M. (Eds.), Compendium of Scott, J.C., Stefaniak, J., Pawlowski, Z.S., McManus, D.P., 1997. Molecular genetic

Cystic Echinococcosis in Africa and in Middle Eastern Countries with Special analysis of human cystic hydatid cases from Poland: identification of a new

Reference to Morocco. Brigham Young University, Provo Utah, genotypic group (G9) of Echinococcus granulosus. Parasitology 114 (Pt 1),

pp. 245–277. 37–43.

Mbaya, H., Magambo, J., Njenga, S., Zeyhle, E., Mbae, C., Mulinge, E., Wassermann, Sharma, M., Sehgal, R., Fomda, B.A., Malhotra, A., Malla, N., 2013. Molecular

M., Kern, P., Romig, T., 2014. Echinococcus spp. in central Kenya: a different characterization of Echinococcus granulosus cysts in north Indian patients:

story. Parasitol. Res. 113, 3789–3794. identification of G1, G3, G5 and G6 genotypes. PLoS Negl. Trop. Dis. 7, e2262.

McManus, D.P., Thompson, R.C., 2003. Molecular epidemiology of cystic Shul’ts, R.S., 1962. On the epidemiology of echinococcosis and methods of its

echinococcosis. Parasitology 127 (Suppl), S37–S51. control. Med. Parasite 31, 272.

McManus, D.P., Zhang, L., Castrodale, L.J., Le, T.H., Pearson, M., Blair, D., 2002. Short Simsek, S., Eroksuz, Y., 2009. Occurrence and molecular characterization of

report: molecular genetic characterization of an unusually severe case of Echinococcus granulosus in Turkish mouflon (Ovis gmelinii anatolica). Acta Trop.

hydatid disease in Alaska caused by the cervid strain of Echinococcus 109, 167–169.

granulosus. Am. J. Trop. Med. Hyg. 67, 296–298.

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

Parasitol. (2015), http://dx.doi.org/10.1016/j.vetpar.2015.07.035

G Model

VETPAR-7722; No. of Pages 9 ARTICLE IN PRESS

T. Romig et al. / Veterinary Parasitology xxx (2015) xxx–xxx 9

Smyth, J.D., 1977. Strain differences in Echinococcus granulosus, with special Varcasia, A., Canu, S., Kogkos, A., Pipia, A.P., Scala, A., Garippa, G., Seimenis, A.,

reference to the status of equine hydatidosis in the United Kingdom. Trans. R. 2007. Molecular characterization of Echinococcus granulosus in sheep and goats

Soc. Trop. Med. Hyg. 71, 93–100. of Peloponnesus, Greece. Parasitol. Res. 101, 1135–1139.

Snabel, V., Altintas, N., D’Amelio, S., Nakao, M., Romig, T., Yolasigmaz, A., Gunes, K., Varcasia, A., Garippa, G., Pipia, A.P., Scala, A., Brianti, E., Giannetto, S., Battelli, G.,

Turk, M., Busi, M., Hüttner, M., Sevcova, D., Ito, A., Dubinsky, P., 2009. Cystic Poglayen, G., Micagni, G., 2008. Cystic echinococcosis in equids in Italy.

echinococcosis in Turkey: genetic variability and first record of the pig strain Parasitol. Res. 102, 815–818.

(G7) in the country. Parasitol. Res. 105, 145–154. Verster, A.J., 1965. Review of Echinococcus species in South Africa. Onderstepoort J.

Soriano, S.V., Pierangeli, N.B., Pianciola, L., Mazzeo, M., Lazzarini, L.E., Saiz, M.S., Vet. Res. 32, 7–118.

Kossman, A.V., Bergagna, H.F., Chartier, K., Basualdo, J.A., 2010. Molecular Vogel, H., 1955. Über den Entwicklungsgang und die Artzugehörigkeit des

characterization of Echinococcus isolates indicates goats as reservoir for Europäischen Alveolar Echinococcus. Dtsch. Med. Wochenschr 80, 931–932.

Echinococcus canadensis G6 genotype in Neuquen, Patagonia Argentina. Vogel, H., 1957. Über den Echinococcus muItilocularis Süddeutschlands. I. Das

Parasitol. Int. 59, 626–628. Bandwurmstadium von Stämmen menschlicher und tierischer Herkunft. Z.

Sweatman, G.K., Williams, R.J., 1963. Comparative studies on the biology and Tropenmed. Parasitol. 8, 404–454.

morphology of Echinococcus granulosus from domestic livestock, moose and Vural, G., Baca, A.U., Gauci, C.G., Bagci, O., Gicik, Y., Lightowlers, M.W., 2008.

reindeer. Parasitology 53, 339–390. Variability in the Echinococcus granulosus cytochrome C oxidase 1

Szidat, L., 1960. Echinococcus patagonicus sp. nov. (Cestoda) parasito del zorro mitochondrial gene sequence from livestock in Turkey and a re-appraisal of

Dusicyon culpaeus culpaeus (Mol.). Neotropica 6, 13–16. the G1-3 genotype cluster. Vet. Parasitol. 154, 347–350.

Szidat, L., 1967. Echinococcus pampeanus—Una nueva specie de la Argentina, Wassermann, A., Aschenborn, O., Aschenborn, J., Mackenstedt, U., Romig, T., 2015.

parasito de Felis colocolo pajeros Desmarest 1916 (Cestoda). Neotropica 13, A sylvatic lifecycle of Echinococcus equinus in the Etosha National Park,

90–96. Namibia. Int. J. Parasitol. Parasites Wildl. 4, 97–103, in press.

Szidat, L., 1971. Echinococcus cepanzoi sp. nov. (Cestoda Taeniidae) del zorro gris, Webster, G.A., Cameron, T.W.M., 1961. Observations on experimental infections

Dusicyon gymnocercus, de la provincia de Buenos Aires. Neotropica 17, 1–4. with Echinococcus in rodents. Can. J. Zool. 39, 877–889.

Tang, C., Cui, G., Qian, Y., Kang, Y., Wang, Y., Peng, W., Lu, H., Chen, D., 2007. Studies Williams, R.J., Sweatmen, G.K., 1963. On the transmission, biology and morphology

on the alveolar Echinococcus species in northward Daxingan mountains, Inner of Echinococcus granulosus equinus, a new subspecies of hydatid tapeworm in

Mongolia, China. III. Echinococcus russicensis sp. nov. Chin. J. Zoonoses 23, horses in Great Britain. Parasitology 53, 391–407.

957–963. Wilson, J.F., Diddams, A.C., Rausch, R.L., 1968. Cystic hydatid disease in Alaska. A

Tappe, D., Kern, P., Frosch, M., 2010. A hundred years of controversy about the review of 101 autochthonous cases of Echinococcus granulosus infection. Am.

taxonomic status of Echinococcus species. Acta Trop. 115, 167–174. Rev. Respir. Dis. 98, 1–15.

Thompson, R.C., 2008. The taxonomy, phylogeny and transmission of Echinococcus. Worbes, H., Thompson, R.C., Eckert, J., 1989. Occurrence of the cattle strain of

Exp. Parasitol. 119, 439–446. Echinococcus granulosus in the German Democratic Republic. Parasitol. Res. 75,

Thompson, R.C., Boxell, A.C., Ralston, B.J., Constantine, C.C., Hobbs, R.P., Shury, T., 495–497.

Olson, M.E., 2006. Molecular and morphological characterization of Xiao, N., Qiu, J., Nakao, M., Li, T., Yang, W., Chen, X., Schantz, P.M., Craig, P.S., Ito, A.,

Echinococcus in cervids from North America. Parasitology 132, 439–447. 2005. Echinococcus shiquicus n. sp., a taeniid cestode from Tibetan fox and

Thompson, R.C., Kumaratilake, L.M., Eckert, J., 1984. Observations on Echinococcus plateau in China. Int. J. Parasitol. 35, 693–701.

granulosus of cattle origin in Switzerland. Int. J. Parasitol. 14, 283–291. Xiao, N., Qiu, J., Nakao, M., Li, T., Yang, W., Chen, X., Schantz, P.M., Craig, P.S., Ito, A.,

Thompson, R.C., Lymbery, A.J., Constantine, C.C., 1995. Variation in Echinococcus: 2006. Echinococcus shiquicus, a new species from the Qinghai-Tibet plateau

towards a taxonomic revision of the genus. Adv. Parasitol. 35, 145–176. region of China: discovery and epidemiological implications. Parasitol. Int. 55

Thompson, R.C., McManus, D., 2001. Aetiology: parasites and life-cycles. In: Eckert, (Suppl), S233–S236.

J., Gemmell, M.A., Meslin, F.X., Pawowski, Z.S. (Eds.), WHO/OIE Manual on Yanagida, T., Mohammadzadeh, T., Kamhawi, S., Nakao, M., Sadjjadi, S.M., Hijjawi,

Echinococcosis in Humans and Animals: A Public Health Problem of Global N., Abdel-Hafez, S.K., Sako, Y., Okamoto, M., Ito, A., 2012. Genetic

Concern. World Health Organisation / World Organisation of Animal Health, polymorphisms of Echinococcus granulosus sensu stricto in the Middle East.

Paris, pp. 1–16. Parasitol. Int. 61, 599–603.

Thompson, R.C., McManus, D.P., 2002. Towards a taxonomic revision of the genus Zhang, L., Gasser, R.B., Zhu, X., McManus, D.P., 1999. Screening for different

Echinococcus. Trends Parasitol. 18, 452–457. genotypes of Echinococcus granulosus within China and Argentina by

Umhang, G., Richomme, C., Hormaz, V., Boucher, J.M., Boue, F., 2014. Pigs and wild single-strand conformation polymorphism (SSCP) analysis. Trans. R. Soc. Trop.

boar in Corsica harbor Echinococcus canadensis G6/7 at levels of concern for Med. Hyg. 93, 329–334.

public health and local economy. Acta Trop. 133, 64–68.

Please cite this article in press as: Romig, T., et al., Taxonomy and molecular epidemiology of Echinococcus granulosus sensu lato. Vet.

Parasitol. (2015), http://dx.doi.org/10.1016/j.vetpar.2015.07.035